1. Field of the Invention
The present invention relates to an optical transmission method and system for carrying data transmission with the use of optical fiber. More particularly, it concerns an optical transmission method and system preferable in high-speed data transmission over a long distance.
2. Description of the Related Art
Prior Art related to the optical transmission system includes, for example, the technique disclosed in the Japanese Patent Application Laid-Open 3-296334.
However, it is demanded to accomplish an optical transmission system operating at further higher speed since development of the modern information society has increased long-distance communication traffic in recent years. Also, it is desired that the optical transmission system can transmit data even longer distances without repeaters to increase reliability and decrease cost of the system. Furthermore, the number of fields to which an optical transmission system is applied has been increased with the recent development of the information society. For this reason, it is needed to achieve an optical transmission system having a variety of functions and the capacity to satisfy various specific requirements.